1. Field of Invention
The present invention relates to a Cu--Sn based sintered, sliding material. More particularly, the sliding material according to the present invention is used in a sliding bearing where corrosion-resistance against the lubricating oil or wear-resistance is required. When the opposed shaft of the sliding bearing has a rough surface and/or is made of material, such as cast iron, a part of the material, particularly graphite, is easily removed during sliding to form a rough surface. The sliding material is worn out by the rough surface, which may be formed either by machining or partial removal of the material during sliding.
2. Description of Related Arts
Bronze and lead bronze, which are used in a large amount for a bush, are sliding materials which exhibit excellent wear-and load-resistance. However, along with a recent change in the conditions under which sliding bearings are used particularly, increase in the surface pressure and rise in the temperature of lubricating oil, bearing troubles due to wear frequently occur. Hard matters are therefore added to the sintered lead-bronze which is sintered on a steel sheet, so as to enhance the wear-resistance such that it can meet to the recent change in the conditions under which the sliding material is used.
The sliding material proposed in Japanese Examined Patent Publication No. 57-50,844 filed by the present assignee is characterized in that its composition is from 10 to 40% of Pb, from 1 to 30% of hard matter, the balance being Cu; or from 10 to 40% of Pb, from 1 to 30% of hard matter, from 0.1 to 10% of Sn and/or from 0.1 to 5% of Sb, the balance being Cu. The hard matter used is Mo, Co, Fe.sub.3 P, FeB, Fe.sub.2 B, or a Ni or Co-based self-fluxing alloy having a particular composition. Since the Pb content of this sliding material is from 10 to 40% the compatibility is improved. However, the effect of the hard matter is not thoroughly exhibited because a portion of the hard matter included in the Pb matrix is removed from the matrix during sliding. In addition, since the Pb content is from 10 to 40%, preferential corrosion of Pb is likely to occur when the temperature of the lubricating oil is from 120.degree. to 130.degree. C. Such corrosion occurred when the above-mentioned sliding material was used in an automatic transmission.